The present invention relates to a method and apparatus for inducing contraction of paralyzed muscles of a limb and also to a method and apparatus for transporting a person having a paralyzed limb by using the afflicted limb to power or propel the apparatus.
A growing number of persons with spinal cord injuries and other central nervous system disorders are receiving electrically-induced exercises as a part of their clinical rehabilitation program. When injury occurs to the spinal cord, neurons that connect the brain with lower motor neurons are often damaged. Alpha motor neurons below the level of the lesion remain healthy, even though communication from brain to alpha motor neurons is lost. In the absence of such communication, muscle groups in the paralyzed limb become debilitated through a process known as disuse atrophy. Continued muscle disuse results in adverse effects upon the heart and cardiovascular system, reduces blood volume, demineralizes bones, and causes muscle atrophy. Petrofsky, Phillips, Heaton and Glaser, Bicycle Ergometer for Paralyzed Muscle, 9:1 Journal of Clinical Engineering 13 (Mar., 1984).
Functional electrical stimulation of debilitated muscles has been demonstrated to improve the physical capacities of individuals with damage to their central nervous systems. Debilitated muscles can be restored to near normal function by electrical stimulation. Indeed, limited numbers of these individuals can now stand for long periods, power tricycles, and even walk with the aid of such stimulation.
Heretofore, apparatus utilized to evoke movement of paralyzed limbs have either used uninvolved i.e., unparalyzed, limbs (without electrical stimulation of paralyzed limbs) or have electrically stimulated paralyzed limbs without requiring concurrent exercise of uninvolved limbs. For example, a stationary patient-initiated response device and method for reeducating debilitated muscle tissue is disclosed in U.S. Pat. No. 4,582,049, issued Apr. 15, 1986, to Ylvisaker. This device is stationary and requires the use of hands only to operate switches, which trigger stimulation of the paralyzed limbs. A wheelchair powered by electrically stimulated paralyzed limbs is disclosed in U.S. Pat. No. 4,523,769, issued June 18, 1985 to Glaser et al. But, this device requires only the momentary manual operation of electrical switches to initiate stimulation of paralyzed limbs, i.e., uninvolved upper limbs are only minimally involved in the operation of this device. Indeed, switches operated by any uninvolved body part would suffice in initiating stimulation of paralyzed limbs in this wheelchair. In another device, an on-board computer is used to control electrical stimulation of paralyzed lower limbs of adults to propel a tricycle, as described by Petrofsky, Phillips, Heaton and Glaser, Bicycle Ergometer for Paralyzed Muscle, supra. This device requires no exercise of uninvolved limbs to initiate electrical stimulation of paralyzed lower limbs, i.e., electrical stimulation is fully computer-controlled. Dependence on a computer system (including stimulator and electrodes) and paralyzed limbs to propel this vehicle put the user at risk of being stranded if computer malfunction or fatigue of paralyzed limbs occurs.